Some characteristics of hormone (pheromone) processing enzymes in yeast

Abstract

The KEX2 gene‐encoded, membrane‐bound Ca²⁺‐dependent thiol endoproteinase, proteinase yscF, responsible for processing of the precursor protein of the sex pheromone α‐factor of the yeast Saccharomyces cerevisiae was solubilized from the membraneous fraction and partially purified. Gel filtration revealed an apparent M_r of the native protein of around 150 000. Ca²⁺ concentration for half‐maximal activity was in the micromolar range and concentration of the substrate Cbz‐Tyr‐Lys‐Arg‐4‐nitroanilide for half‐maximal velocity was 0.05 mM. The enzyme is able to cleave basic amino acids from the carboxy‐terminus of peptides and probably involved in final maturation of the α‐factor peptides generated by proteinase yscF is membrane‐associated, active at neutral pH and responds strongly to the serine proteinase inhibitor phenylmethylsulfonyl fluoride as well as to ‐SH group blocking agents.